The goal of the research is to determine how pulsatory fluid flux in an artery wall can influence endothelial cell desquamation and concentration polarization. We have measured the hydraulic conductivity of endothelial layers and the hydraulic conductivity per unit thickness of media tissue. These data, along with the mechanical properties of the artery and available mathematical models of water flux in arteries, predict that when arterial pressure is increased: a) the interstitial pressure in the media should decrease, and b) the accompanying hydraulic gradient should cause fluid to be imbibed by the media. Our experiments on dog aortas in vivo and in vitro show that the pressure behaves qualitatively as predicted above but that fluid flux is in the opposite direction from that predicted in (b). In the experiments proposed in the coming year, we will explore the anomalous result. Our initial hypothesis is that water drawn from strained arterial smooth muscle cells alters the osmolarity in the interstitial space so that the osmotic driving force for fluid movement outweighs the hydraulic driving force. Accordingly, we will measure shifts in intracellular volumes in arteries fixed at varying pressures and measure the osmotic pressure as well as the hydrostatic pressure in the vessel wall when the wall is subjected to controlled strains. The influence of this fluid movement through the endothelial layer on desquamation and polarization will then be evaluated.